The present invention relates to a connection element and a connecting device for tubes for medical use.
As is well known, in the medical field it is often necessary to set up fluid communication between pipes designed to carry liquids.
At the present time, to create a mechanical connection between consecutive terminal portions of two tubes, use may be made of connector elements attachable to the mutually opposing ends of the two tubes to be connected. Each connector element comprises a first portion that attaches onto the terminal portion of the respective tube, and a second portion designed for removable engagement on the other connector element. The mechanical connection between the two connectors is typically provided by threaded or bayonet couplings, Luer connections and the like.
It is however clear that connector devices described above can only provide a mechanical connection between the two terminal portions of tube and, if necessary, ensure the necessary fluidtightness.
There are however medical applications in which it is required to be able easily to create the mechanical connection between the two tubes that are to be joined up, but also to control the flow passing through the connected tubes. More specifically, if two fluid-transport lines are to be connected to each other, it is often necessary to stop the flow when the two lines are disconnected and allow the flow of fluid to resume immediately the two lines are properly connected.
With reference for example to peritoneal dialysis, there is typically a need to set up a connection between a line attached to the patient, in fluid communication with the interior of the peritoneum, and at least one infusion/drainage line designed to carry fluids to or from the patient's peritoneum.
To this end, if it is wished to use the connectors described above, the patient or an operator can make the physical connection between the line attached to the patient and a terminal portion of the infusion/evacuation line.
For the system to work properly, the infusion/evacuation lines and the tube connected to the patient must each have clamps or flow-prevention members, typically positioned in the vicinity of the terminal portion of the respective tube and capable of being adjusted from an open condition, in which they do not act on their respective tube, and a closed condition, in which they squeeze the tube so that the flow of fluid through the latter is stopped. In other words, the fixed line connected to the patient's peritoneum and the infusion/evacuation line must be fitted with suitable means capable of preventing the fluid leaking out until the operator has connected the two lines together.
From the operational point of view, a precise procedure must be followed when carrying out any connection operation between the infusion/evacuation line and the portion of tube connected to the patient: first of all any closure members situated at the end of each connector must be removed, and then the mechanical connection must be made between the line connected to the patient and the infusion/evacuation line, and finally the clamps must be opened.
From the above description is clear that a great deal of manipulation by the hands is required to make and break the connection. This is due to the structure of the connectors and to the fact that the connectors and flow-prevention elements (clamps) employed are functionally independent of each other.
In addition to this, the solution described can be seen to be favourable in certain situations to bacterial growth.
Specifically, the section of line extending between each flow-prevention clamp and the end of the tube is only wetted by the flow during use. Although, theoretically, at the beginning and end of each treatment this section undergoes a washing and disinfecting procedure, it is obvious that great care is required on the part of the user to reduce the possibility of bacterial growth.
In view of the limitations of the connectors described above, other technical approaches have been developed in the past and these will now be briefly described.
U.S. Pat. No. 5,743,892 discloses a connection system for peritoneal dialysis comprising a first connector on a tube attachable to patient and a second connector attached to an infusion/drainage tube. During coupling of the two connectors, an annular element on the second connector disinfects a coupling portion of the first connector. The connectors also include a clamp which can be operated by hand to prevent or regulate the flow through said connectors.
This approach fails to solve the problem of the complex hand movements required, as the functions of mechanical connection and flow prevention are separate. Also, the clamps of each connector operate at a distance from the free end of said connector, only partly solving the problems of bacterial growth outlined above.
Another known approach, designed to improve the problems of connecting and disconnecting a peritoneal dialysis line, is disclosed in patent EP 0 724 464. This document illustrates a connection system comprising a first connection element connected to an infusion/drainage line and a second connection element connected to a fixed line in fluid communication with the peritoneum of a patient. When the two connectors are being mechanically coupled, a pusher on the first connector angularly displaces a pivoting shutter on the second connector. In this way the lines connected to the first and second connectors are placed in fluid communication.
Besides the evident structural and constructional complication, the approach described above can only work if the second connector has a clamp to ensure that the flow cannot get through the second connector when the first is disengaged. In fact the second connector of the system described in EP 0 724 464 has a clamp on a section at a distance from the inlet-outlet section of said connector. In practice, the connection system described above evidences substantially the same limitations as the other known solutions.
There are also technical solutions that use a connector element defining in its interior a fluid passage between an inlet opening and an outlet opening and capable of performing the functions of both mechanical compression and, at the same time, flow regulation. In particular, U.S. Pat. No. 5,730,418 discloses a connector comprising a resilient shut-off element able to move from an open condition, in which it lets the fluid through, to a closed condition, in which an active portion of the resilient element positions itself flush with an inlet opening of the connector to stop the flow as desired. The solution described in U.S. Pat. No. 5,730,418 requires however that the internal deformable element has a highly asymmetric structure, in such a way as to fold up upon itself when a male element is inserted through the access opening. Despite the fact that this configuration allows flow to be opened when desired, it also defines a tortuous path for the flow of fluid through the connector, with obvious areas where the fluid can stagnate, and significant pressure losses, especially at high flowrates.
It should be pointed out that the presence of a “clean” flow with few or no areas of stagnation helps to improve the quality of the flow in fluid dynamic terms and helps to reduce the possibility of bacterial developing and growing.